<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>

    <style>
        article{
            position: relative;
            width: 500px;
            height: 500px;
            border: 1px solid blueviolet;
            box-sizing: border-box;
        }

        div{
            width: 100px;
            height: 100px;
            background-color: burlywood;
            position: absolute;
            left: 50%;
            top: 50%;
            margin-left: -50px;
            margin-top: -50px;

        }
    </style>
    
    <article>
        <div></div>
    </article>
</body>
</html>